Carbon dioxide is a greenhouse gas whose concentration is increasing in the atmosphere due to combustion of fossil fuels. Carbon dioxide absorbs infrared radiation and thus traps heat in the atmosphere. In this respect it acts like the glass walls of a greenhouse, and hence it is referred to as a greenhouse gas. Since CO2 traps heat in the atmosphere, the increasing carbon dioxide concentration in the atmosphere is altering our climate by increasing global temperatures and altering rain and snowfall patterns. This is likely to cause widespread ecological damage, species extinction, flooding of low-lying coastal areas, and harm agriculture in certain areas.
To avoid a runaway greenhouse effect, humanity will need to reduce fossil fuel use, increase use of renewable energy that produces no net greenhouse gas emissions, and decrease carbon dioxide release from fossil fuel burning. Methods to decrease CO2 release from fossil fuel use, increase energy yield from fossil fuel combustion, or increase the yield of renewable energy are needed.